727 Transmission year?

can any one tell me how to find out what year 727 tranny I have? do the have some sort of marking on them and where would it be?
Your numbers are going to be I want to say passenger side but I'm not sure just where the oil pan connect to. Just above that. Let's see how can I put this visual into writing. If the transmission was sitting on your bench and you tried to flick your nail on the edge of the oil pan you'd actually be touching where the numbers are on the side also right there on that little quarter inch of flat spot right where the oil pan attaches to on the side of the transmission.